One thing I'm seeing is that the improvers on questionnaire scores look like outliers. Nearly everyone is still in the same clumps they were in at the start of the trial.
The other thing is that there's no similar outliers in the objective measurement, the 6 Minute Walk Test (6MWT). Even the very highest scores are on the poor end of average, so it would suggest these weren't healthy people at the end of the trial.
Put those two together, and I think we're seeing the effects of a bit of brainwashing upon a small minority: self-reports claim improvement, but they can't keep up on the objective performance measures.